Fabrication method for dual damascene structure

Abstract

A fabrication method for a dual damascene structure is described wherein a substrate covered by a HSQ layer is provided. An E-beam curing is conducted on the HSQ layer where the via hole is to be formed. Photolithography and etching are further conducted on the HSQ layer to form a trench. Since the E-beam cured HSQ layer and the thermally cured HSQ layer have a high etching selectively ratio, the HSQ layer that has not been E-beam cured can be wet etched to from a via hole. A dual damascene structure is formed after filling the trench and the via hole with a conductive material, wherein either the via hole or the trench can be first formed.

What is claimed is:  
     
       1. A fabrication method for a dual damascene structure comprising: 
       providing a substrate;  
       forming a hydrogen silsequioxane layer (HSQ) to cover the substrate;  
       thermal curing the HSQ layer;  
       forming a hard mask layer on the thermal cured HSQ layer to cover a portion of the thermal cured HSQ layer;  
       performing an E-beam curing on a remaining exposed portion of the thermal cured HSQ layer to transform the remaining exposed portion of the thermal cured HSQ layer into an E-beam cured HSQ layer;  
       removing the hard mask;  
       performing a wet etching to selectively remove the thermal cured HSQ layer to form a via hole and to expose a part of the substrate;  
       forming a patterned photoresist layer on the E-beam cured HSQ layer and a photoresist layer partially filling the via to cover the exposed past of the substrate, wherein the patterned photoresist layer exposes a part of the E-beam cured HSQ layer and the via hole;  
       selectively removing the exposed part of the E-beam cured HSQ layer to form a trench above the via hole;  
       removing the photoresist layer on the E-beam cured HSQ layer and the photoresist layer in the via hole; and  
       forming a conductive material to fill the trench and the via hole.  
     
     
       2. The fabrication method according to claim  1 , wherein the HSQ layer is about 600 nm to about 1800 nm thick. 
     
     
       3. The fabrication method according to claim  1 , wherein the hard mask layer is selected from a group consisting of polysilicon, oxide, silicon nitride, silicon oxy-nitride, titanium nitride, aluminum oxide and carbonated silicon. 
     
     
       4. The fabrication method according to claim  1 , wherein the mask layer is about 10-1000 nm thick. 
     
     
       5. The fabrication method according to claim  1 , wherein parameters for the E-beam curing process includes a substrate temperature of about 300 to about 500 degrees Celsius, a dosage of about 1000 to about 10000 microC./cm 2  and an energy of about 1 to about 20 Kev. 
     
     
       6. The fabrication method according to claim  1 , wherein the thermal curing process is conducted at a temperature of about 300 to about 500 degrees Celsius. 
     
     
       7. The fabrication method according to claim  1 , wherein the HSQ layer is replaced by a spin-on-glass layer. 
     
     
       8. A fabrication method for a dual damascene structure, comprising: 
       providing a substrate;  
       forming a HSQ layer to cover the substrate;  
       thermal curing the HSQ layer;  
       forming a hard mask layer on the HSQ layer to cover a portion of the thermal cured HSQ layer;  
       E-beam curing, a remaining exposed portion of the thermal cured HSQ layer to transform the remaining exposed thermal cured HSQ layer into an E-beam cured HSQ layer;  
       removing the hard mask layer;  
       forming a patterned photoresist layer on the E-beam cured HSQ layer, wherein the patterned photoresist layer exposes the thermal cured HSQ layer;  
       removing a portion of the E-beam cured HSQ layer and a portion of the thermal cured HSQ layer using the photoresist layer as a mask to form a trench;  
       removing the photoresist layer;  
       wet etching the remaining thermal cured HSQ layer to form a via hole under the trench and exposing a portion of the substrate; and  
       forming a conductive material to- fill the trench and the via hole.  
     
     
       9. The fabrication method according to claim  8 , wherein the HSQ layer is about 600 to about 1800 nm thick. 
     
     
       10. The fabrication method according to claim  8 , wherein a material for the mask layer is selected from the group consisting of polysilicon, oxide, silicon nitride, silicon oxy-nitride, titanium nitride, aluminum oxide and carbonated silicon. 
     
     
       11. The fabrication method according to claim  8 , wherein the hard mask layer is about 10 nm to about 1000 nm thick. 
     
     
       12. The fabrication method according to claim  8 , wherein parameters for the E-beam curing process includes a substrate temperature of about 300 degrees Celsius to about 500 degree Celsius, a dosage of about 1000 microC./cm 2  to about 10000 microC./cm 2 , and an energy of about 1 to about 20 Kev. 
     
     
       13. The fabrication method according to claim  8 , wherein the thermal curing is conducted at a temperature of about 300 degrees Celsius to about 500 degrees Celsius.